A high-power bidirectional DCDC converter and a control method thereof

Abstract

The application discloses a high-power bidirectional DCDC converter and a control method thereof. The high-power bidirectional DCDC converter comprises at least two BUCK-BOOST units in staggered parallel connection, and the BUCK-BOOST unit comprises a switching tube, a first capacitor, a second capacitor, a first resistor, a second resistor and a third resistor. The high-power bidirectional DCDC converter provided by the application improves the reliability of TCM soft switching control of the high-power BUCK-BOOST, reduces the switching tube loss, improves the system efficiency, reduces the system harmonic interference, reduces the filtering cost, and realizes high-efficiency and low-cost control of the high-power converter.

Description

Technical Field

[0001] This invention relates to the field of electrical engineering, and specifically to a high-power bidirectional DC-DC converter and its control method. Background Technology

[0002] Bidirectional DC / DC converters are widely used in the new energy industry. The most common topology for bidirectional converters is BUCK-BOOST (boost-buck inverter), but its efficiency is low, limiting its application. Some low-power BUCK-BOOST converters use TCM (triangle current control mode) soft-switching control to improve efficiency, but in high-power converters (above 5kW), due to the large machine current and poor current detection resolution during soft switching, TCM soft-switching control is difficult to implement.

[0003] Traditional high-power BUCK-BOOST switches are limited by the relatively small junction capacitance current of the switching transistor compared to the system current, large switching interference, and insufficient current detection, making it impossible to achieve reliable TCM soft-switching control. Summary of the Invention

[0004] In view of the above problems, the present invention is proposed to provide a high-power bidirectional DC-DC converter and its control method that overcome or at least partially solve the above problems.

[0005] According to one aspect of the present invention, a high-power bidirectional DC-DC converter is provided, comprising at least two BUCK-BOOST units connected in alternating parallel configurations. Each BUCK-BOOST unit includes a switching transistor, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a voltage sampling module. The collector of the switching transistor is simultaneously connected to one end of the first capacitor and one end of the first resistor. The other end of the first resistor is simultaneously connected to one end of the second resistor, one end of the second capacitor, and the voltage sampling module. The emitter of the switching transistor is simultaneously connected to the other end of the first capacitor and one end of the third resistor. The other end of the third resistor is simultaneously connected to the other end of the second resistor, the other end of the second capacitor, and the voltage sampling module.

[0006] Optionally, the converter further includes a main controller, and the voltage sampling module is connected to the main controller.

[0007] Optionally, the high-power bidirectional DC-DC converter further includes a PWM controller, one end of which is connected to the main controller and the other end is connected to the base of the switching transistor.

[0008] Optionally, the converter further includes a current sampling module connected to the main controller.

[0009] Optionally, the converter further includes an inductor, one end of which is connected to the current sampling module.

[0010] Optionally, the main controller may include a DSP (Digital Signal Processor), an ARM, an FPGA (Field Programmable Gate Array), or a MCU (Microcontroller Unit).

[0011] Optionally, the high-power bidirectional DC-DC converter further includes a diode, the negative terminal of which is connected to both the collector of the switching transistor and one end of the first capacitor, and the positive terminal of which is connected to both the emitter of the switching transistor and the other end of the first capacitor.

[0012] Optionally, the high-power bidirectional DC-DC converter includes a first BUCK-BOOST unit and a second BUCK-BOOST unit connected in alternating parallel configuration.

[0013] According to another aspect of the present invention, a control method for a high-power bidirectional DC-DC converter is provided, comprising the following steps:

[0014] S1. Turn off the switch of the first BUCK-BOOST unit and turn on the switch of the second BUCK-BOOST unit;

[0015] S2. Turn off the switching transistors of the first BUCK-BOOST unit and the second BUCK-BOOST unit, and add judgment condition 1 as the condition to satisfy the switching transistor in the first BUCK-BOOST unit to be turned on.

[0016] S3, the switching transistor of the first BUCK-BOOST unit turns on at zero voltage and turns off after a preset time;

[0017] S4. When the inductor current in the circuit is close to the minimum value, add judgment condition 2 as a condition to satisfy the switching transistor in the second BUCK-BOOST unit to turn on. If judgment condition 2 is satisfied, the switching transistor of the second BUCK-BOOST unit will be turned on with zero voltage.

[0018] Optionally, the judgment condition 1 includes IL≥0 and Vcs11≤Vdsth, where IL is the inductor current, Vcs11 is the voltage across the first capacitor in the first BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switch.

[0019] Optionally, the judgment condition 2 includes IL≤0 and Vcs12≤Vdsth, where IL is the inductor current, Vcs12 is the voltage across the first capacitor in the second BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switch.

[0020] According to another aspect of the present invention, an electronic device is provided, comprising: a memory and a processor;

[0021] The memory is used to store program instructions;

[0022] The processor is used to call program instructions in the memory to execute the control method of the high-power bidirectional DC-DC converter described above.

[0023] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein computer program instructions are stored therein, and when the computer program instructions are executed, the control method of the high-power bidirectional DC-DC converter described above is implemented.

[0024] According to another aspect of the present invention, a computer program product is provided, comprising a computer program that, when executed by a processor, implements the control method of the high-power bidirectional DC-DC converter described above.

[0025] As described above, the technical solution of this invention provides a high-power bidirectional DC-DC converter. By employing interleaved parallel connection, parallel capacitors for switching transistors, and increased switching transistor voltage detection, it improves the reliability of TCM soft-switching control of high-power BUCK-BOOST, reduces switching transistor losses, increases system efficiency, reduces system harmonic interference, lowers filtering costs, and achieves efficient and low-cost high-power converter control. Specifically, parallel capacitors for switching transistors can resolve differences in parasitic capacitance between switches and adjust the minimum value at inductor resonance. Adding voltage detection (Vds) across the switching transistors to the traditional BUCK-BOOST, combined with current detection, enables more precise TCM soft-switching control than traditional single current control. Utilizing switching transistor voltage detection (Vds) for partial protection improves switching reliability. The converter employs multi-phase interleaved parallel connection, reducing the current of each BUCK-BOOST unit, increasing the ratio of module control current to total system current, and improving inductor current detection resolution. Simultaneously, the interleaved parallel connection of BUCK-BOOST units effectively reduces input and output ripple current, lowering filtering costs. Attached Figure Description

[0026] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0027] Figure 1 A schematic diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown;

[0028] Figure 2A schematic diagram of a BUCK-BOOST unit in a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown;

[0029] Figure 3 A basic principle block diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown.

[0030] Figure 4 A basic logic block diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown. Detailed Implementation

[0031] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0032] Figure 1 A schematic diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown.

[0033] like Figure 1 As shown, the high-power bidirectional DC-DC converter includes two BUCK-BOOST units connected in alternating parallel configurations.

[0034] Figure 2 A schematic diagram of a BUCK-BOOST unit in a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown.

[0035] like Figure 2 As shown, the BUCK-BOOST unit includes a switching transistor, a first capacitor, a second capacitor C1, a first resistor R1, a second resistor R2, a third resistor R3, and a voltage sampling module. The collector of the switching transistor is connected to one end of the first capacitor and one end of the first resistor R1. The other end of the first resistor R1 is connected to one end of the second resistor R2, one end of the second capacitor C1, and the voltage sampling module. The emitter of the switching transistor is connected to the other end of the first capacitor and one end of the third resistor R3. The other end of the third resistor R3 is connected to the other end of the second resistor R2, the other end of the second capacitor C1, and the voltage sampling module. The voltage sampling module can use resistor sampling, which is low-cost and highly reliable.

[0036] Figure 3 A basic principle block diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown.

[0037] like Figure 3 As shown, the high-power bidirectional DC-DC converter also includes a main controller, and the voltage sampling module is connected to the main controller. One end of the PWM controller is connected to the main controller, and the other end is connected to the base of the switching transistor. The converter also includes a current sampling module CUR-S1, which is connected to the main controller. The converter also includes an inductor L1, one end of which is connected to the current sampling module CUR-S1. The current sampling module uses a sampling circuit composed of common Hall effect sensors, shunts, etc.

[0038] Optionally, the main controller may include, but is not limited to, a DSP, an ARM, an FPGA, and an MCU. In specific implementations, the DSP, ARM, FPGA, and MCU can be distributed into separate modules, each controlled independently.

[0039] In one embodiment of the present invention, the high-power bidirectional DC-DC converter further includes a diode, wherein the negative terminal of the diode is connected to both the collector of the switching transistor and one end of the first capacitor, and the positive terminal of the diode is connected to both the emitter of the switching transistor and the other end of the first capacitor.

[0040] In one embodiment of the present invention, the converter in the above method includes a first BUCK-BOOST unit and a second BUCK-BOOST unit connected in alternating parallel configuration.

[0041] According to another aspect of the present invention, a control method for a high-power bidirectional DC-DC converter is provided, comprising the following steps:

[0042] S1. Turn off the switch Q11 of the first BUCK-BOOST unit and turn on the switch Q12 of the second BUCK-BOOST unit;

[0043] S2. Turn off the switching transistors of the first BUCK-BOOST unit and the second BUCK-BOOST unit, and add judgment condition 1 as the condition for the switching transistor Q11 in the first BUCK-BOOST unit to be turned on; the judgment condition 1 includes IL≥0 and Vcs11≤Vdsth, where IL is the inductor current, Vcs11 is the voltage across the first capacitor Cs11 in the first BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switching transistor.

[0044] S3, the switching transistor Q11 of the first BUCK-BOOST unit turns on at zero voltage and turns off after a preset time;

[0045] S4. When the inductor current in the circuit is close to the minimum value, a judgment condition 2 is added as a condition to satisfy the switching transistor Q12 in the second BUCK-BOOST unit to turn on. If the judgment condition 2 is satisfied, the switching transistor Q12 in the second BUCK-BOOST unit will be turned on with zero voltage. The judgment condition 2 includes IL≤0 and Vcs12≤Vdsth, where IL is the inductor current, Vcs12 is the voltage across the first capacitor Cs12 in the second BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switching transistor.

[0046] For details, please refer to Figure 4 , Figure 4 A basic logic block diagram of a high-power bidirectional DC-DC converter according to an embodiment of the present invention is shown.

[0047] During the 0 to t1 stage, Q11 is off and Q12 is on, the inductor stores energy, and the inductor current IL continues to increase.

[0048] During the t1 to t2 phase, Q11 and Q12 are turned off, inductor L and capacitor Cs12 resonate, Cs12 charges, Cs11 discharges, and the inductor freewheels through the diode inside Q11.

[0049] At this point, add judgment condition 1: IL≥0 and Vcs11≤Vdsth, Q11 satisfies the activation condition.

[0050] At time t2, Q11 turns on with zero voltage.

[0051] During the t2 to t3 stage, the inductor energy is released and the inductor current IL continues to decrease. When the inductor current turns negative at t3, the inductor current turns negative.

[0052] During the t3 to t4 period, the inductor current IL continues to decrease negatively.

[0053] At time t4, Q11 is turned off.

[0054] During the t4 to t5 stage, the inductor current approaches its minimum value Imin, and the inductor L resonates with Cs11 and Cs12. Cs11 charges, Cs12 discharges, and the internal diode of Q12 freewheels.

[0055] At this point, condition 2 is added: IL≤0 and Vcs12≤Vdsth, Q12 meets the turn-on condition. At t5, Q12 is turned on at zero voltage.

[0056] The above loop, based on traditional control, adds judgment conditions 1 and 2, which can filter out false start-up caused by harmonic current.

[0057] It should be noted that:

[0058] The algorithms and displays provided herein are not inherently related to any particular computer, virtual device, or other equipment. Various general-purpose devices can also be controlled in conjunction with the teachings herein. The required structure for constructing such devices is apparent from the above description. Furthermore, this invention is not directed to any particular programming language. It should be understood that the contents of the invention described herein can be implemented using various programming languages, and the above description of specific languages ​​is for the purpose of disclosing the best mode of implementation of the invention.

[0059] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0060] Similarly, it should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, in the above description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, inventive aspects lie in fewer than all features of a single foregoing disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into this detailed description, wherein each claim itself is a separate embodiment of the invention.

[0061] Those skilled in the art will understand that modules in the device of the embodiments can be adaptively changed and placed in one or more devices different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component. Except where at least some of such features and / or processes or units are mutually exclusive, any combination can be used to combine all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or device so disclosed. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0062] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features but not others included in other embodiments, combinations of features from different embodiments are intended to be within the scope of the invention and form different embodiments. For example, in the following claims, any of the claimed embodiments can be controlled in any combination.

[0063] The various component embodiments of the present invention can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that, in practice, a microprocessor or digital signal processor (DSP) can be controlled to implement some or all of the functions of some or all of the components in the DC-DC converter according to embodiments of the present invention. The present invention can also be implemented as a device or apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such programs implementing the present invention can be stored on a computer-readable medium or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0064] It should be noted that the above embodiments are illustrative of the invention and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The invention can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The words first, second, and third, etc., do not indicate any order. These words can be interpreted as names.

Claims

1. A control method for a high-power bidirectional DC-DC converter, characterized in that, This technology is applied to high-power bidirectional DC-DC converters, which include at least two staggered parallel BUCK-BOOST units. Each BUCK-BOOST unit includes a switching transistor, a first capacitor, a second capacitor, a first resistor, a second resistor, a third resistor, and a voltage sampling module. The collector of the switching transistor is connected to one end of the first capacitor and one end of the first resistor, and the other end of the first resistor is connected to one end of the second resistor, one end of the second capacitor, and the voltage sampling module. The emitter of the switching transistor is connected to both the other end of the first capacitor and one end of the third resistor. The other end of the third resistor is connected to the other end of the second resistor, the other end of the second capacitor, and the voltage sampling module. The method includes the following steps: S1. Turn off the switch of the first BUCK-BOOST unit and turn on the switch of the second BUCK-BOOST unit; S2. Turn off the switching transistors of the first BUCK-BOOST unit and the second BUCK-BOOST unit, and add judgment condition 1 as the condition to satisfy the switching transistor in the first BUCK-BOOST unit to be turned on. S3, the switching transistor of the first BUCK-BOOST unit turns on at zero voltage and turns off after a preset time; S4. When the inductor current in the circuit is close to the minimum value, add judgment condition 2 as a condition to satisfy the switching transistor in the second BUCK-BOOST unit to turn on. If judgment condition 2 is satisfied, the switching transistor of the second BUCK-BOOST unit will be turned on with zero voltage. The judgment condition 1 includes IL≥0 and Vcs11≤Vdsth, where IL is the inductor current, Vcs11 is the voltage across the first capacitor in the first BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switch. The judgment condition 2 includes IL≤0 and Vcs12≤Vdsth, where IL is the inductor current, Vcs12 is the voltage across the first capacitor in the second BUCK-BOOST unit, and Vdsth is the real-time voltage measured by the sampling switch.

2. An electronic device, characterized in that, include: Memory and processor; The memory is used to store program instructions; The processor is used to call program instructions in the memory to execute the control method of the high-power bidirectional DC-DC converter as described in claim 1.

3. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer program instructions, which, when executed, implement the control method for the high-power bidirectional DC-DC converter as described in claim 1.

4. A computer program product, comprising a computer program, characterized in that: When the computer program is executed by the processor, it implements the control method for the high-power bidirectional DC-DC converter as described in claim 1.

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